Project summary/Abstract While cure rates for pediatric acute lymphoblastic leukemia (ALL) have improved dramatically over the last several decades, ALL remains the second leading cause of cancer-related death in children. There continues to be an unmet need for effective therapies for patients with T-cell acute lymphoblastic leukemia (T-ALL), particularly those with relapsed or refractory disease. T-ALL is a disease generally responsive to drugs targeting metabolism, including methotrexate and asparaginase, which form the backbone of T-ALL therapy. Thus, I hypothesize that novel approaches to targeting metabolism may be particularly relevant in T-ALL. I screened a panel of leukemia cell lines against small-molecule inhibitors of methylene tetrahydrofolate dehydrogenase 2 (MTHFD2) and serine hydroxymethyltransferase 2 (SHMT2), enzymes of the mitochondrial one carbon folate pathway, and I discovered that T-ALL cells are highly sensitive to these inhibitors, more so than other leukemia cell lines. This proposal aims to use the small molecule inhibitors of MTHFD2 and SHMT2, as well as genetic suppression of these enzymes, in vitro and in vivo, to study the mechanistic role of SHMT2 and MTHFD2 in T-ALL pathogenesis. The ultimate goal of the project is to develop novel therapies for patients with T-ALL. I am a pediatric oncologist who is seeking K08 support for mentored time in Dr. Kimberly Stegmaier's laboratory at DFCI, with Dr. Matthew Vander Heiden at MIT as a co-mentor. My long-term career goal is to become an independent academic physician-scientist, using genomic and chemical approaches to identify metabolic vulnerabilities in acute leukemia with an eye toward therapeutic intervention. My prior research experiences have established my skills in functional genomics, molecular and cellular biology and drug testing applied to acute myeloid leukemia and T-ALL. I am now well positioned to establish the necessary expertise in cancer metabolism, translational medicine and developmental therapeutics through the critical mentored K08 award. The Dana-Farber Cancer Institute (DFCI)/Boston Children's Hospital, Massachusetts Institute of Technology (MIT) and the Broad Institute of MIT and Harvard are internationally recognized research programs with a number of expert researchers in the areas of hematopoiesis, metabolism and cancer cell biology, among others. The DFCI Division of Pediatric Oncology has a distinguished record of training young physician- scientists for leadership roles in pediatric cancer research. I have assembled an excellent mentoring and advisory committee, consisting of Dr. Nika Danial, Dr. Jon Aster, and Dr. Lewis Silverman, who will guide my research and training experiences. With the structured mentoring, educational, and research plans, I will acquire the necessary expertise to become a successful independent investigator in translational cancer metabolism.